1. Field of the Invention
The present invention relates to a light adjusting apparatus.
2. Description of the Related Art
A wide variety of systems have been conventionally implemented as light adjusting apparatuses. As one of such systems, a drop-in type light adjusting apparatus (e.g., drop-in iris) in which a single or a plurality of optical elements are mutually moved into and away from an optical path by an electromagnetic driving source or a different type of driving source to vary optical characteristics of the incident light passing through the optical path is known.
In recent years, along with improvements in image resolution and quality of small imaging devices such as mobile gear having an imaging capability or micro video scopes, the demand for the adoption of an adjustable focus lens, an adjustable diaphragm and an optical-characteristic variable filter than optical elements such as a lens, a diaphragm and an optical filter instead of a conventional fixed-focus lens, a conventional fixed diaphragm and a conventional optical-characteristic invariable filter, respectively, has been keen. As a light adjusting apparatus applicable to such small imaging devices, the aforementioned drop-in type light adjusting apparatus has been attracting attention as a light adjusting apparatus suitable for miniaturization because the drop-in type light adjusting apparatus is simple in structure.
As an example of such a drop-in type light adjusting apparatus suitable for miniaturization is disclosed in Japanese Patent No. 4021077. In this patent, a rotor coupled to shutter blades is supported by a shaft and a hole which are formed on a shutter base plate and a cover frame, respectively, in a manner to be rotatable, and this support structure stabilizes the rotational movement of the rotor (see FIG. 2 and other figures of Japanese Patent No. 4021077).
However, in the structure disclosed in Japanese Patent No. 4021077, the cover frame and the shutter base plate need to be joined to each other with high precision so that the aforementioned shaft, which is formed on the shutter substrate, the aforementioned rotor, and the aforementioned hole, which is formed on the cover frame, are aligned on a common axis.
If the axes of the aforementioned shaft, rotor and hole mutually deviate, this deviation becomes an obstacle to the rotational movement of the rotor. On the other hand, if the tolerance in displacement between these axes is set to a great value, the rotational movement of the rotor becomes unstable, which is a problem.
The influence caused by the assembling accuracy of components such as described above becomes noticeable as the device decreases in size, and it becomes extremely difficult to achieve a configuration such as disclosed in Japanese Patent No. 4021077 if the size of the light adjusting apparatus is in the order of a few millimeters.